Chico Formation

The Chico Formation is a geologic formation of the Campanian Age during the Cretaceous Period, found in California and southern Oregon.

Chico Formation
Stratigraphic range: Campanian Age, Cretaceous Period
Type	Geological formation
Underlies	Martinez Formation (regionally), Tejon Formation (regionally)
Overlies	Vaqueros Formation
Lithology
Primary	sandstone
Location
Region	California, Oregon
Country	United States
Type section
Named for	Chico, California

Geology

The MesozoicEra formation can regionally overlie the Vaqueros Formation, and can regionally underlie the Martinez Formation or Tejon Formation.

The Chico Formation is exposed in the Southern California Coast Ranges, western San Joaquin Valley, north of Mount Diablo, and in the Chico area of the northeastern Sacramento Valley.^[1]

It is also found in the eastern Simi Hills in Bell Canyon and Dayton Canyon, located in Los Angeles and Ventura Counties, near the community of West Hills.^[1]

Paleofauna

Dinosaur remains are among the fossils that have been recovered from the formation, from the Late Cretaceous of the Mesozoic Era.^[1][2]

Species

The lizard and bird species listed in the table below date from the Late Cretaceous Epoch.^[1][3][4]

Vertebrates of the Chico Formation
Genus	Species	Location	Member	Abundance	Notes	Images
Clidastes[5]						Hesperornis
Hesperornis[6]
Ichthyornis[6]
indet. Pteranodontidae[7]

See also

• California portal
• Paleontology portal

• List of fossiliferous stratigraphic units in California
  • List of dinosaur-bearing rock formations
  • List of stratigraphic units with indeterminate dinosaur fossils
• Paleogene California
• Paleontology in California